Isolation, structure modification, and anti-rheumatoid arthritis activity of isopimarane-type diterpenoids from Orthosiphon aristatus.

Orthosiphon aristatus is a well-known folkloric medicine and herb for Guangdong soup for the treatment of rheumatism in China. Eight isopimarane-type and migrated pimarane-type diterpenoids (1-8), including a new one with a rarely occurring α,ß-unsaturated diketone C-ring, were isolated from O. aristatus. Their structures were determined by spectroscopic methods and quantum chemical calculations. Furthermore, the most abundant compound, orthosiphol K, was structurally modified by modern synthetic techniques to give seven new derivatives (9-15). The anti-rheumatoid arthritis activity of these diterpenoids were evaluated on a TNF-α induced MH7A human rheumatoid fibroblast-like synoviocyte model. Compound 10 showed the most potent activity among these compounds. Based on their inhibitory effects on the release levels of IL-1ß, the preliminary structure-activity relationships were concluded. Furthermore, western blot analysis revealed that 10 could increase the expression of IκBα and decrease the expression of NF-κB p65, and the expression levels of COX-2 and NLRP3 proteins were consequently down-regulated.

[A new benzopyran glycoside from Gentiana macrophylla].

Thirteen compounds were isolated and identified from 70% ethanol extract of the roots of Gentiana macrophylla by multi-chromatographic methods, including microporous resin, silica gel, and C_(18) reversed-phase column chromatography, as well as HPLC as follows: macrophylloside G(1), macrophylloside D(2), 5-formyl-2,3-dihydroisocoumarin(3),(+)-medicarpin(4),(+)-syringaresinol(5), liquiritigenin(6),(3R)-sativanone(7),(3R)-3'-O-methylviolanone(8), 4,2',4'-trihydroxychalcone(9), latifolin(10), gentioxepine(11), 6α-hydroxycyclonerolidol(12), and ethyl linoleate(13). Compound 1 was a new benzopyran glycoside. Compounds 4, 6-10, 12, and 13 were isolated for the first time from Gentiana plants. Compounds 1 and 2 showed promising hepatoprotective activity against D-GalN-induced AML12 cell damage at the concentration of 10 µmol·L~(-1), and compound 2 exhibited more significant activity than silybin at the same concentration.

Terpenoid Glucosides from Gentiana macrophylla That Attenuate TNF-α Induced Pulmonary Inflammation in A549 Cells.

Four previously undescribed terpenoid glucosides, including one sesquiterpenoid di-glucoside (1), two new iridoid glucosides (2, 3), and a new triterpenoid tri-glucoside (4), were isolated from a 70% ethanol extract of the root of Gentiana macrophylla (Gentianaceae), along with eight known terpenoids. Their structures were determined by spectroscopic techniques, including 1D, 2D NMR, and HRMS (ESI), as well as chemical methods. The absolute configuration of compound 1 was determined by quantum chemical calculation of its theoretical electronic circular dichroism (ECD) spectrum. The sugar moieties of all the new compounds were confirmed to be D-glucose by GC analysis after acid hydrolysis and acetylation. Anti-pulmonary inflammation activity of the iridoids were evaluated on a TNF-α induced inflammation model in A549 cells. Compound 2 could significantly alleviate the release of proinflammatory cytokines IL-1ß and IL-8 and increase the expression of anti-inflammatory cytokine IL-10.

(±)-Heterocageflavone, anti-inflammatory isoprenylated flavonoids with a tricyclo[5.3.1.03,8]undecane moiety from Artocarpus heterophyllus.

(±)-Heterocageflavone (1), a pair of enantiomeric isoprenylated flavonoids, were isolated from Artocarpus heterophyllus. Compound 1 incorporates an unusual tricyclo[5.3.1.03,8]undecane moiety, forming a unique caged polycyclic system. The structures of the pair were determined by spectroscopic analysis, ECD calculations, and single-crystal X-ray diffraction. Compound 1 showed significant inhibitory activity against LPS-induced NO production in RAW264.7 cells with an IC50 value of 49.2 µM.

Structural Elucidation of Three 9,11-Seco Tetracyclic Triterpenoids Enables the Structural Revision of Euphorol J.

Compounds 1-3, the rare examples of 9,11-seco euphane or lanostane triterpenoids featuring an enol-hemiacetal functionality, were isolated from Euphorbia stracheyi. Their structures were elucidated by a combination of spectroscopic, computational, chemical, and single-crystal X-ray diffraction means, which enables the structure of previously published euphorol J to be revised as 1. 1-3 showed significant cytotoxicities on the breast cancer cell line MDA-MB-468 with IC50 values in the range of 2.9-3.9 µM.

Horienoids A and B, Two Heterocoupled Sesquiterpenoid Dimers from Hedyosmum orientale.

Two eudesmane-guaiane/lindenane heterocoupled sesquiterpenoid dimers, horienoids A (1) and B (2) with new carbon skeletons, from Hedyosmum orientale were characterized by a combined method. Compound 1 featured a unique 2,10-dioxabicyclo[6.2.1]undecane core moiety with an anti-Bredt bridgehead double bond. Their biogenetic pathways were proposed to involve Diels-Alder and cascade rearrangement reactions as the key steps. Compound 2 exhibited a potent anti-inflammatory effect on LPS-induced BV-2 microglial cells.

An Efficient Regioselective Synthesis of 8-Formylhomoisoflavonoids with Neuroprotective Activity by Enhancing Autophagy.

6-Formylisoophiopogonone B (7a) and 8-formylophiopogonone B (7b), two natural products isolated from Ophiopogon japonicus, represent a subgroup of rare 6/8-formyl/methyl-homoisoflavonoid skeletons. Herein we report an efficient method for the synthesis of these formyl/methyl-homoisoflavonoids. The synthesized compounds were evaluated for their neuroprotective effects on the MPP+-induced SH-SY5Y cell injury model and showed marked activity. Exploration of the neuroprotective mechanisms of compound 7b led to an increased expression of autophagy marker LC3-II and down-regulation of autophagy substrate p62/SQSTM1. Molecular docking studies showed that 7b may prevent the inhibition of the classic PI3K-AKT-mTOR signaling pathway by interfering with the human HSP90AA1.

Pseudosterins A-C, Three 1-Ethyl-3-formyl-ß-carbolines from Pseudostellaria heterophylla and Their Cardioprotective Effects.

Pseudostellaria heterophylla is used in China not only as a functional food but also as an herb to tonify the spleen, enhance immunity, and treat palpitation. Our previous investigation showed that a fraction enriched in glycosides obtained from the roots of P. heterophylla possessed pronounced protective effects on H9c2 cells against CoCl2-induced hypoxic injury. However, the active compounds responsible for the observed effects were still unknown. In the current investigation, pseudosterins A-C (1-3), three new alkaloids with a 1-ethyl-3-formyl-ß-carboline skeleton, together with polydatin, have been isolated from the active fraction. Their structures were elucidated on the basis of spectroscopic analysis and quantum chemical calculations. The four compounds showed cardioprotective effects against sodium hydrosulfite-induced hypoxia-reoxygenation injury in H9c2 cells, with the three alkaloids being more potent. This is also the first report of alkaloids with a ß-carboline skeleton isolated from P. heterophylla as cardioprotective agents.

[A new phenylethanol glycoside from Baphicacanthis Cusiae Rhizoma et Radix].

The 95% ethanol extract of Baphicacanthis Cusiae Rhizoma et Radix was purified by multi-chromatographic methods including microporous resin, silica gel, Sephadex LH-20, and C_(18) reversed-phase column chromatography. Fourteen compounds were isolated and structurally identified, including five phenylethanoid glycosides, five phenylpropanoids, one lupinane triterpene, two alkaloids, and one flavonoid, listed as follows: 2-(4-hydroxy-3-methoxyphenyl)-3-(2-hydroxy-5-methoxyphenyl)-3-oxo-1-propanol B(1), threo-2,3-bis-(4-hydroxy-3-methoxybenzene)-3-methoxypropanol(2), 2-(3-hydroxy-4-methoxyphenyl)-ethanol-1-O-[3,4-O-di-acetyl-(1→3)-O-α-L-rhamnopyranosyl]-ß-D-glucopyranoside(3), verbascoside(4), 2″,3″-di-O-acetyl martynoside(5),(+)-pinore-sinol(6), diospyrosin(7), daidzein(8), wiedemannioside B(9), buddlenol A(10), 2″-O-acetyl martyonside(11), lupeol(12), indirubin(13), and tryptanthrin(14). Compound 3 was a new phenylethanoid glycoside, and the other 10 compounds were isolated for the first time from Baphicacanthis Cusiae Rhizoma et Radix except compounds 12, 13, and 14.

A Cryptic Plant Terpene Cyclase Producing Unconventional 18- and 14-Membered Macrocyclic C25 and C20 Terpenoids with Immunosuppressive Activity.

A versatile terpene synthase (LcTPS2) producing unconventional macrocyclic terpenoids was characterized from Leucosceptrum canum. Engineered Escherichia coli and Nicotiana benthamiana expressing LcTPS2 produced six 18-/14-membered sesterterpenoids including five new ones and two 14-membered diterpenoids. These products represent the first macrocyclic sesterterpenoids from plants and the largest sesterterpenoid ring system identified to date. Two variants F516A and F516G producing approximately 3.3- and 2.5-fold, respectively, more sesterterpenoids than the wild-type enzyme were engineered. Both 18- and 14-membered ring sesterterpenoids displayed significant inhibitory activity on the IL-2 and IFN-γ production of T cells probably via inhibition of the MAPK pathway. The findings will contribute to the development of efficient biocatalysts to create bioactive macrocyclic sesterterpenoids, and also herald a new potential in the well-trodden territory of plant terpenoid biosynthesis.

Acid/Base-Tunable Unimolecular Chirality Switching of a Pillar[5]azacrown Pseudo[1]Catenane.

Stimuli-responsive unimolecular chirality switching is a highly intriguing topic because the molecular structure as well as its function can be adjusted simultaneously by a switching process. Herein, a novel acid/base-tunable unimolecular chirality switching system based on a pillar[5]azacrown pseudo[1]catenane is reported. The bicyclic pillar[5]azacrown pseudo[1]catenane PN4 is synthesized through fusing an azacrown ring onto one repeating unit of a pillar[5]arene. Protonation and deprotonation can reversibly regulate the conformational transformations of PN4 between self-inclusion and self-exclusion structures, which results in the chiroptical inversions of the pseudo[1]catenane. NMR spectra, circular dichroism spectra, and single-crystal structures demonstrate these processes. This pseudo[1]catenane is a novel pillararene-based unimolecular chirality switching system driven by acid/base responsiveness and reveals a new perspective on the supramolecular chirality chemistry of macrocycles.

Classification of Flavonoid Metabolomes via Data Mining and Quantification of Hydroxyl NMR Signals.

Utilizing the distinct HMBC cross-peak patterns of lower-field range (LFR; 11.80-14.20 ppm) hydroxyl singlets, presented NMR methodology characterizes flavonoid metabolomes both qualitatively and quantitatively. It enables simultaneous classification of the structural types of 5-OH flavonoids and biogenetically related 2'-OH chalcones, as well as quantification of individual metabolites from 1H NMR spectra, even in complex mixtures. Initially, metabolite-specific LFR 1D 1H and 2D HMBC patterns were established via literature mining and experimental data interpretation, demonstrating that LFR HMBC patterns encode the different structural types of 5-OH flavonoids/2'-OH chalcones. Taking advantage of the simplistic multiplicity of the H,H-uncoupled LFR 5-/2'-OH singlets, individual metabolites could subsequently be quantified by peak fitting quantitative 1H NMR (PF-qHNMR). Metabolomic analysis of enriched fractions from three medicinal licorice (Glycyrrhiza) species established proof-of-concept for distinguishing three major structural types and eight subtypes in biomedical applications. The method identified 15 G. uralensis (GU) phenols from the six possible subtypes of 5,7-diOH (iso)flav(an)ones with 6-, 8-, and nonprenyl substitution, including the new 6-prenyl-licoisoflavanone (1) and two previously unknown compounds (4 and 7). Relative (100%) qNMR established quantitative metabolome patterns suitable for species discrimination and plant metabolite studies. Absolute qNMR with combined external and internal (solvent) calibration (ECIC) identified and quantified 158 GU metabolites. HMBC-supported qHNMR analysis of flavonoid metabolomes ("flavonomics") empowers the exploration of structure-abundance-activity relationships of designated bioactivity. Its ability to identify and quantify numerous metabolites simultaneously and without identical reference materials opens new avenues for natural product discovery and botanical quality control and can be adopted to other flavonoid- and chalcone-containing taxa.

Daphnillonins A and B: Alkaloids Representing Two Unknown Carbon Skeletons from Daphniphyllum longeracemosum.

Two highly rearranged daphniphyllum alkaloids, daphnillonins A (1) and B (2), were isolated from Daphniphyllum longeracemosum and structurally characterized by a combination of diverse methods, including the calculation of electronic circular dichroism. Compound 1 possesses an unprecedented carbon architecture with a very unique 8-methyl-6-azabicyclo[3.2.1]octane moiety, and compound 2 represents a new carbon skeleton with an uncommon 7/6/5/7/5/5-fused ring system. The biosynthetic pathways for the two alkaloids were proposed with the concurrent major alkaloids as the precursors.

Maximumins A-D, Rearranged Labdane-Type Diterpenoids with Four Different Carbon Skeletons from Amomum maximum.

Four highly rearranged labdane-type diterpenoids, maximumins A-D (1-4) possessing different new carbon skeletons, together with a biosynthetically related known analog 5 were isolated from Amomum maximum. The structures of new compounds with absolute configurations were characterized by spectroscopic and computational approaches. The plausible biogenetic pathways for 1-4 were proposed. These compounds showed moderate to weak activities against nuclear factor kappa B (NF-κB).

Proanthocyanidin Dimers and Trimers from Vitis vinifera Provide Diverse Structural Motifs for the Evaluation of Dentin Biomodification.

Aimed at exploring the dentin biomodification potential of proanthocyanidins (PACs) for the development of dental biomaterials, this study reports the phytochemical and dental evaluation of nine B-type PACs from grape seed extract (GSE). Out of seven isolated dimers (1-7), four new compounds (2, 3, 5, and 6) involved relatively rare ent-catechin or ent-epicatechin monomeric flavan-3-ol units. Low-temperature NMR analyses conducted along with phloroglucinolysis and electronic circular dichroism enabled unequivocal structural characterization and stereochemical assignment. Additionally, one known (8) and one new (9) B-type trimer were characterized. Differential 13C NMR chemical shifts (Δδ) were used to determine the absolute configuration of 9, relative to the dimers 1 and 2 as the possible constituent subunits. Compared to the dimers, the trimers showed superior dentin biomodification properties. The dimers, 1-7, exhibited pronounced differences in their collagenase inhibitory activity, while enhancing dentin stiffness comparably. This suggests that PAC structural features such as the degree of polymerization, relative and absolute configuration have a differential influence on enhancement of dentin biomechanical and biostability. As mechanical enhancement to dentin and resistance to proteolytic biodegradation are both essential properties functional and stable dentin substrate, the structurally closely related PACs suggest a new metric, the dentin biomodification potential (DBMP) that may rationalize both properties.

Euphorhelipanes A and B, Triglyceride-Lowering Euphorbia Diterpenoids with a Bicyclo[4.3.0]nonane Core from Euphorbia helioscopia.

Euphorhelipanes A (1) and B (2), two Euphorbia diterpenoids with a new 4-(5,5-dimethylheptan-2-yl)-2,7-dimethylbicyclo[4.3.0]nonane skeleton, were isolated from a 95% ethanol extract of the whole plants of Euphorbia helioscopia. Their structures were elucidated by spectroscopic data analysis, quantum chemical calculations, and single-crystal X-ray diffraction data. Compounds 1 and 2 represent the first examples of Euphorbia diterpenoids with a 5/6 fused carbon ring system, and their plausible biosynthetic pathways originating from jatrophanes are proposed. Compounds 1 and 2 showed a triglyceride-lowering effect in oleic-acid-stimulated HuH7 cells at concentrations of 1-50 µM.

Triterpenoids from Cyclocarya paliurus that Enhance Glucose Uptake in 3T3-L1 Adipocytes.

Four previously undescribed compounds, including three rarely occurring seco-dammarane triterpenoid glycosides and a pentacyclic triterpenic acid, were isolated from a 70% ethanol extract of the leaves of Cyclocarya paliurus (Juglandaceae), along with eleven known triterpenoids. Their structures were determined by spectroscopic techniques, including 2D NMR and HRESIMS, as well as chemical methods. Among them, several triterpenoids enhanced insulin stimulated glucose uptake in both 3T3-L1 adipocytes and C2C12 myotubes. Furthermore, compound 1 dose-dependently increased glucose uptake through activating AMP-activated protein kinase (AMPK)-p38 pathway. Collectively, triterpenoids from C. paliurus could be developed as insulin sensitizers, which might have therapeutic potential for insulin resistance and hyperglycemia.

[A new spirocyclic cycloartane triterpenoid from Souliea vaginata].

The 70% ethanol extract of the whole plant of Souliea vaginata was purified by multi-chromatographic methods including macroporous resin,silica gel,Sephadex LH-20,and C18-reversed-phase column chromatography. A new spirocyclic cycloartane triterpenoid was isolated and identified as( 16 R*,20 R*,23 S*,24 R*,25 S*)-16,23: 23,26-diepoxy-15α,24,25-trihydroxy-9,19-cycloart-3ß-O-ß-D-xylopyranoside( 1),and named as soulieoside S. Its planar structure and relative configuration were determined by spectroscopic techniques including 2 D NMR and HRESI-MS. As one of the main components of S. vaginata,compound 1 was evaluated for its anti-inflammatory activity by a lipopolysaccharide( LPS)-stimulated NO production model in RAW264. 7 macrophages,but it didn't show NO production inhibitory effect.

Colocynthenins A-D, Ring-A seco-Cucurbitane Triterpenoids from the Fruits of Citrullus colocynthis.

Four ring-A seco-cucurbitane triterpenoids, colocynthenins A-D (1-4), together with seven known cucurbitane triterpenoids (5-11), were isolated from the fruits of Citrullus colocynthis. Their structures and absolute configurations were elucidated based on spectroscopic analysis and quantum chemical ECD calculations. Compound 1 possesses an unprecedented 2,11-lactone moiety, while compound 2 is the first reported cucurbitane triterpenoid with an unusual cyano group. Compounds 1 and 3 showed acetylcholinesterase inhibitory activities in a standard in vitro assay, with IC50 values of 2.6 and 3.1 µM, respectively.

Absolute Configuration of Native Oligomeric Proanthocyanidins with Dentin Biomodification Potency.

The structurally complex oligomeric proanthocyanidins (OPACs) are promising biomimetic agents, capable of strengthening the macromolecular backbone of teeth via intermolecular and intermicrofibrillar cross-linking. This study establishes analytical methods capable of determining the absolute configuration of the catechin-type monomeric units of underivatized OPACs. This preserves the capacity of their biological evaluation, aimed at understanding the inevitably stereospecific interactions between the OPACs and dentin collagen. Guided by dental bioassays (modulus of elasticity, long-term stability), two new trimeric and tetrameric A-type OPACs were discovered as dentin biomodifiers from pine (Pinus massoniana) bark: epicatechin-(2ß→O→7,4ß→8)-epicatechin-(2ß→O→7,4ß→8)-catechin (5) and epicatechin-(2ß→O→7,4ß→8)-epicatechin-(2ß→O→7,4ß→6)-epicatechin-(2ß→O→7,4ß→8)-catechin (6), respectively. Combining 1D/2D NMR, HRESIMS, ECD, 1H iterative full spin analysis (HiFSA), and gauge-invariant atomic orbital (GIAO) δ calculations, we demonstrate how 13C NMR chemical shifts (diastereomeric building blocks (A-type dimers)) empower the determination of the absolute configuration of monomeric units in the higher oligomers 5 and 6. Collectively, NMR with ECD reference data elevates the level of structural information achievable for these structurally demanding molecules when degradation analysis is to be avoided. Considering their numerous and deceptively subtle, but 3D impactful, structural variations, this advances the probing of OPAC chemical spaces for species that bind selectively to collagenous and potentially other biologically important biomacromolecules.